One of the classical concepts concerning the cortical control of movement is that the primary motor cortex receives a significant input from 'premotor' areas in the frontal lobe. These premotor areas are thought to be important 'links in the chain of command' from cortical areas in the prefrontal and parietal lobe to the primary motor cortex. Physiological and behavioral studies suggest that the premotor areas may be particularly important for the proper sequencing of motor tasks, the structuring of skilled movement, and the guidance of limb movements in extrapersonal space. We have identified 4 spatially separate 'premotor areas' in the frontal lobe which project directly to the primary motor cortex. Each of the premotor areas is somatotopically organized and appears to contain a complete representation of the body. The focus is to define one aspect of the output organization of the premotor areas, i.e, their contribution to the corticospinal system. To accomplish this aim we will: 1) Determine the origin of corticospinal projections from the premotor areas to different levels of the cervical and lumbar spinal cord; 2) Determine the pattern of termination of corticospinal projections from each premotor area to the cervical spinal cord; 3) Determine the motor effects produced by intracortical stimulation within each premotor area. The studies will provide some new insights into whether each of the premotor areas has direct access to spinal cord mechanisms involved in the generation and control of limb movement. In addition, the studies will provide an anatomical and physiological framework for future studies which examine the function of corticospinal projections from the premotor areas during movement.